STUDY OF THE OUTPUT CHARACTERISTICS OF TURBOCOMPRESSORS OF MODERN AGRICULTURAL MACHINERY

The main causes of malfunction of turbocharged internal combustion engines are high dynamic loads, significant thermal loads in friction zones, wear of turbocharger elements, overheating of components and systems, oil starvation, etc. The reliability of the output parameters of the turbochargers depending on the variable input data values. A condition has been obtained for the trouble-free operation of turbocharger bearings, taking into account oil pumping at engine start, which makes it possible to determine the limits of turbocharger performance and to exclude failure cases with a guarantee. A methodology has been developed for analyzing the sensitivity of the run-out time with oil parameters and turbocharger operation modes, which makes it possible to evaluate the correct operation of turbochargers of modern automotive vehicles in operation. The main test object is K27-145 turbocharger installed on KAMAZ vehicles. The rotor shaft speed, depending on the configuration, is 40.000...120.000 min-1. During the implementation of the experimental work, the working frequency range of rotation of the turbocharger rotor shaft was provided from 25.000 to 75.000 min-1. The levels of variation of rotational speeds were chosen from the condition of providing the maximum frequency - 75000 min-1, the frequency corresponding to average loads - 50000 min-1 and the minimum at which the boost pressure rises to the level of atmospheric pressure - 25000 min-1. The results of the experiment, carried out within a wide range of changes in the input parameters of the oil at the input values of the oil pressure - 0.1 ... 0.4 MPa and the temperatures of the input oil into the bearing - 50 ... run-out from variable input parameters. The run-out time of K27-145 turbocharger rotor at speeds of 25.000, 50.000 and 75.000 min-1 is 10.3…14.8 s, respectively; 28.1…34.4 s; 38.6…47.1 s. The sensitivity of the run-out time with an increase in the rotational speed from 25000 to 75000 min-1 with a variation of 25000 min-1 increases and for the same frequency values it is - 6.6 ... 8.3 s/MPa; 10.6…14.3 s/MPa; 12.0…18.6 s/MPa. Control of run-out time sensitivity parameters allows to determine the quality of the process of assembly and running-in of turbocharger units in the factory, in operation - the correct functioning and resource of the turbocharger. The developed method of rundown control is recommended for machine-building, car service and training organizations.